Embodiments of the present invention relate generally to biological or chemical analysis and more particularly to systems and methods using detection devices for biological or chemical analysis.
Various protocols in biological or chemical research involve performing a large number of controlled reactions on local support surfaces or within predefined reaction chambers. The desired reactions may then be observed or detected and subsequent analysis may help identify or reveal properties of chemicals involved in the reaction. For example, in some multiplex assays, an unknown analyte having an identifiable label (e.g., fluorescent label) may be exposed to thousands of known probes under controlled conditions. Each known probe may be deposited into a corresponding well of a microplate. Observing any chemical reactions that occur between the known probes and the unknown analyte within the wells may help identify or reveal properties of the analyte. Other examples of such protocols include known DNA sequencing processes, such as sequencing-by-synthesis (SBS) or cyclic-array sequencing.
In some conventional fluorescent-detection protocols, an optical system is used to direct an excitation light onto fluorescently-labeled analytes and to also detect the fluorescent signals that may emit from the analytes. However, such optical systems can be relatively expensive and require a larger benchtop footprint. For example, the optical system may include an arrangement of lenses, filters, and light sources. In other proposed detection systems, the controlled reactions occur immediately over a solid-state imager (e.g., charged-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) detector) that does not require a large optical assembly to detect the fluorescent emissions.
However, the proposed solid-state imaging systems may have some limitations. For example, it may be challenging to distinguish the fluorescent emissions from the excitation light when the excitation light is also directed toward the light detectors of the solid-state imager. In addition, fluidicly delivering reagents to analytes that are located on an electronic device and in a controlled manner may present additional challenges. As another example, fluorescent emissions are substantially isotropic. As the density of the analytes on the solid-state imager increases, it becomes increasingly challenging to manage or account for unwanted light emissions from adjacent analytes (e.g., crosstalk).